Anti-e is a partial derivative. In mathematics, the partial derivative of multivariable function is that it is the derivative of one variable and keeps other variables unchanged (all variables in total differential are allowed to change). Partial derivatives are very useful in vector analysis and differential geometry.

Definition of partial derivative

In mathematics, the partial derivative of a multivariable function is its derivative with respect to one variable, while keeping other variables unchanged with respect to the total derivative, in which all variables are allowed to change. Partial derivative is very useful in vector analysis and differential geometry. In univariate function, derivative is the rate of change of function.

It is much more complicated to study the "rate of change" of binary function because there is one more independent variable. On the xOy plane, when the moving point changes from P(x0, y0) to different directions, the changing speed of the function f(x, y) is generally different, so it is necessary to study the edge of f(x, y) at (x0, y0).